Problem: Ishaan is 3 times as old as Stephanie and is also 4 years older than Stephanie. How old is Stephanie?
Explanation: We can use the given information to write down two equations that describe the ages of Ishaan and Stephanie. Let Ishaan's current age be $i$ and Stephanie's current age be $s$ $i = 3s$ $i = s + 4$ Now we have two independent equations, and we can solve for our two unknowns. Since we are looking for $s$ , and both of our equations have $i$ alone on one side, this is a convenient time to use elimination. Subtracting the second equation from the first equation, we get: $0 =$ $3s$ $-$ $ (s + 4)$ which combines the information about $s$ from both of our original equations. Solving for $s$ , we get: $2 s = 4$ $s = 2$.